A drug overdose could be a possible cause of the death of the wife of Union Minister Shashi Tharoor, Sunanda Pushkar.

Shashi Tharoor's statement will be recorded on Monday by the Sub-Divisional Magistrate (SDM).

With doctors declaring her death in a five-star hotel yesterday as "sudden, unnatural" after the autopsy conducted today, the focus of investigations shifted to potential causes that led to the demise of 52-year-old Sunanda Pushkar.

While the final autopsy report will be available in "couple of days", police sources said that it could be a case of drug overdose. However, a final picture would emerge only after toxicological analysis and a complete visco-pathological examination.

Alok Sharma, the SDM probing the sensation death, said tonight that statements of Sunanda Pushkar's son and brother had been recorded and also that of two servants of the Tharoors.

Asked when he would record Shashi Tharoor's statement, he said he was initially planning to do so tomorrow but had been informed that the minister and the family were going to Haridwar. Therefore, it would be recorded on Monday, he said.

Sharma said his inquiry, under Section 176 of CrPC which covers death of a women married for less than seven years, was to find out whether there was any foul play in Sunanda Pushkar's death. Police would carry out their investigations.

The SDM has prepared a list of examinees, whose statements would also be recorded on Monday.

The police has questioned the hotel staff and checked the CCTV footage of the lobby of the third floor of the luxury hotel where Sunanda Pushkar was staying.

Sources in police said call details record of Sunanda Pushkar was also being checked as part of the probe into her death.

Sunanda Pushkar was found dead inside suite no 345 in Leela Palace hotel where she and her minister husband had checked in on Thursday.

Investigators said they are screening the call details record of Pushkar as well as her tweets in the last few days.

They said a number of hotel staff, including those who had gone to the suite, were being questioned to corroborate the version of Shashi Tharoor and his staff.

The police had also searched the suite thoroughly to see whether Sunanda Pushkar had used any medicine, they said, adding it was sealed later.

There were reports that the couple had initially booked two separate rooms in the hotel and later moved to the suite.